Wahoo Fitness KICKR Smart Power Trainer / 11-Speed with RPM Cadence Sensor Size: Both ANT+ and BLE capabilities allow the KICKR to connect with smartphones and GPS devices, simultaneously or separately Wheel-off design for direct, lab accurate power measurement at the hub that is consistent and calibrated throughout every grueling mile (accurate to +/-3%) When connected to your device, it automatically sets your resistance via your favorite app or software High inertia flywheel is engineered to replicate the feel of an actual rider on the road Get all your virtual cycling metrics on your indoor ride (cadence measurement when paired with the included Wahoo Fitness RPM Cadence Sensor)